I often ride 2-up with my gf so I decided to get the HD springs. Progressive's website suggests using the HD ones if 50% or more of your riding time is spent with heavy loads. When it is just myself riding I set the preload to the lowest setting and they feel good without topping. I would suggest going heavy duty unless you never ride with a load or passenger. I'm 5'10" and 160lbs but ride with luggage and passenger a lot.

These springs are a little heavy for me on the cx500. Not the springs fault at all. I guessed wrong. Even though they are a little on the heavy side everything is nice and smooth with the Progressive shocks. Very happy with the purchase.